Which of the following statements about cells is true? A cell is _____.

a. characteristic of eukaryotic but not prokaryotic organisms

b. always between 200 and 500 micrometers in diameter

c. characteristic of both prokaryotic and eukaryotic organisms

d. only found in multiples of two, because single cells cannot exist independently

characteristic of both prokaryotic and eukaryotic organisms

Advertisement
)

Which statement about spontaneous generation is false?

a. It apparently occurred at least oncewhen life on Earth began.

b. It occurs every time a new species evolves from a preexisting species.

c. Pasteur demonstrated that it does not occur under normal laboratory conditions.

d. It addresses the formation of living cells from previously nonliving material.

b. It occurs every time a new species evolves from a preexisting species.

Which part of an amino acid is always acidic?

Amino functional group

Side chain ("R group")

Carboxyl functional group

None of the above

carboxyl functional group

Which of the following statements about the formation of polypeptides from amino acids is true?

Polypeptides form by condensation or hydrolysis reactions.

A bond can form between any carbon and nitrogen atom in the two amino acids being joined.

A bond forms between the carboxyl functional group of one amino acid and the amino functional group of the other amino acid.

The reaction occurs through the addition of a water molecule to the amino acids.

A bond forms between the carboxyl functional group of one amino acid and the amino functional group of the other amino acid.

Why are polymerization reactions endergonic?

They reduce entropy.

They release heat, making the reactant monomers move faster.

The condensation and hydrolysis reactions are equally spontaneous.

Polymers are energetically more stable and have lower potential energy than monomers do.

they reduce entropy

Suppose you discovered a new amino acid. Its R-group contains only hydrogen and carbon atoms. Predict the behavior of this amino acid.

It is hydrophilic.

Relative to the amino acids found in organisms, its interactions with water will be intermediate.

It is hydrophobic.

Relative to the amino acids found in organisms, its interactions with water will be very high.

It is hydrophobic

Consider a situation in which the enzyme is operating at optimum temperature and pH, and has been saturated with substrate. What is your best option for increasing the rate of the reaction?

Increase the pH.

Increase the temperature.

Increase the enzyme concentration.

Increase the substrate concentration.

Increase the enzyme concentration

An enzyme inhibitor that is roughly the same shape as the substrate and binds at the active site is termed a(n) _____ inhibitor.

allosteric

competitive

noncompetitive

catalytic

competitive

Tertiary structure is NOT directly dependent on _____.

hydrogen bonds

ionic bonds

bonds between sulfur atoms

peptide bonds

hydrophobic interactions

peptide bonds

The secondary structure of proteins results because of _____ bonding between atoms in the protein's backbone.

hydrogen

ionic

covalent

hydrophobic

hydrogen

Which of the following is true of protein folding?

Once proteins fold, their structure doesn't change.

Correct folding is aided by high temperatures.

Misfolded proteins can still function correctly.

Some proteins can fold spontaneously.

Some proteins can fold spontaneously.

The main reason that proteins outperform other macromolecules in terms of catalytic ability is because ____.

proteins can contain a variety of R groups

peptide bonds are covalent

proteins are soluble in water

proteins are polymers

Protein can contain a variety of R groups

By convention, biologists write the sequence of amino acids in a polypeptide in which direction?

charged residues to uncharged residues

amino- to carboxy-terminus

carboxy- to amino-terminus

polar residues to nonpolar residues

Amino- to carboxy-terminus

Why are proteins not considered to be a good candidate for the first living molecule?

Their amino acid monomers were likely not present during chemical evolution.

They could not have polymerized on their own from amino acids during chemical evolution.

They cannot serve as a template for replication.

Their catalytic capability is insufficient.

They cannot serve as a template for replication

Advertisement

Nonpolar amino acid residues are typically found in the interior of globular proteins like trypsin. Which chemical force is most directly responsible?

Ionic bonding

Covalent bonding

Tertiary structure

Hydrophobic interaction

Hydrophobic intercations

The condensation reaction that forms nucleic acid polymers occurs between a _____ group on one nucleotide and a _____ group on a second nucleotide.

nitrogenous base, nitrogenous base

carbon, carbon

phosphate, hydroxyl

nitrogenous base, sugar

phosphate, hydroxyl

In a nucleic acid polymer, the hydrogen bonds that help to hold regions of double-strandedness together occur between what parts of the nucleotide monomers?

sugars

nitrogenous bases

sugars, phosphates, and nitrogenous bases

sugars and phosphates

nitrogen bases

Some viruses consist only of a protein coat surrounding a nucleic acid core. If you wanted to radioactively label the nucleic acids separately from the protein, you would use _____.

radioactive phosphorus

radioactive sulfur

radioactive carbon

radioactive nitrogen

radioactive phosphorus

Nucleic acids have a definite polarity, or directionality. Stated another way, one end of the molecule is different from the other end. How are these ends described?

One end has an unlinked 3 carbon; the other end has an unlinked 5 carbon.

Why is it that RNA can catalyze reactions but DNA cannot?

The sugar of RNA is much more reactive than the sugar of DNA.

DNA molecules with a high percentage of guanine (G) and cytosine (C) are particularly stable. Why?

A G-C base pair has three hydrogen bonds, whereas an A-T base pair has two.

Which statement expresses a real difference between DNA and RNA?

(a) DNA can make a double helix; RNA cannot.

(b) DNA is much longer than RNA.

(c) DNA has more kinds of bases than RNA.

Both (a) and (b).

(a), (b), and (c).

DNA is much longer than RNA.-- Remember that RNA is a copy of part of DNA

When double-stranded DNA is heated to 95°C, the bonds between complementary base pairs break to produce single-stranded DNA. Considering this observation, is the strand separation step required for replication of the double helix spontaneous? Why or why not?

No. A continuous input of energy is required

RNA nucleotides contain __________ than DNA nucleotides.

less phosphorusdifferent purinesmore oxygenless oxygenNone of the above.

more oxygen

Researchers hypothesize that the first self-replicating molecule may have been ____. This is known as the ______world hypothesis.

RNA, RNA

lipid, lipid

protein, protein

DNA, RNA

RNA, RNA

What functional groups define the two different ends of a DNA strand?

Check all that apply.

a free hydroxyl group on the 3' carbon

a free phosphate group on the 5' carbon

a free phosphate group on the 3' carbon

a free hydroxyl group on the 5' carbon

a free hydroxyl group on the 3' carbon

a free phosphate group on the 5' carbon

How would you expect the structure of ribozymes in organisms that grow in very hot environments, such as hot springs or deep-sea vents, to differ from those in organisms that grow in cooler environments?

The hairpins would have more G's and C's in the primary structure.

What do cells do to activate nucleotides for incorporation into a polymer and why?

Add phosphate groups to raise the potential energy of monomers.

Which of the following classes of macromolecules always contains a carbohydrate portion?

nucleic acids

None of the listed responses is correct.

water

proteins

nucleic acids

A monosaccharide that has the chemical formula C5 H10 O5 would be characterized as a _____.

RNA

triose

hexose

pentose

pentone

What is the difference between an aldose sugar and a ketose sugar?

the position of the carbonyl group

Glucose (C6H12O6) has a single carbonyl group (-C=O) in its linear form. Based on the number of oxygen atoms in glucose, how many hydroxyl groups (-OH) would you expect glucose to have?

3

1

5

6

5

A glycosidic linkage is a covalent bond that links two _____.

monosaccharides

water molecules

amino acids

nucleotides

monosaccharides

Which of the following linkages would you expect to find at a branch point in glycogen or amylopectin?

α-1,4-glycosidic linkage

β-1,4-glycosidic linkage

α-1,6-glycosidic linkage

β-1,6-glycosidic linkage

α-1,6-glycosidic linkage

Which of the following carbohydrates contains a peptide bond?

cellulose

peptidoglycan

glycogen

Carbohydrates don't contain peptide bonds; only proteins do.

chitin

peptidoglycan

What is the major structural difference between starch and glycogen?

the type of glycosidic linkages in the molecule

the amount of branching that occurs in the molecule

whether glucose is in the α or β form

the types of monosaccharide subunits in the molecules

the amount of branching that occurs in the molecules

Which of the following do starch and cellulose have in common?

their main function in plants

the type of glycosidic linkage used

the size of their monosaccharide subunits

the amount of hydrogen bonding that occurs between parallel strands

the size of their monosaccharids subunits

Enzymes that readily break starch apart cannot hydrolyze the glycosidic linkages found in cellulose. Why is this logical?

The geometry of the bonds is different, and the shapes of enzyme active sites are highly specific.

Peptidoglycan forms sheets that stiffen the cell walls of bacteria. How is the formation of sheets possible?

Individual strands are joined by peptide bonds–a type of covalent bond.

Which polysaccharide is an important component in the structure of many animals and fungi?

chitin

amylose

cellulose

peptidoglycan

chitin

Compare the molecular formula of a carbohydrate (CH2O)n with that of carbon dioxide (CO2). What does the presence of hydrogen atoms in carbohydrates indicate?

Carbohydrates are more reduced than carbon dioxide.

Unmodified sugars (those with the formula C n H2 n O n ) can have ...

(a) H covalently bound to the C of a C=O group.

(b) a C atom that is covalently bound to three H atoms.

(c) the formula C3H6O3.

Both (a) and (c).

Both (b) and (c).

both a and c

A molecule has the formula C n H2 n O n . What else does it need to be an unmodified monosaccharide?

(a) Nothing.

(b) A carboxyl group.

(c) O bound to every C.

(d) At least 5 carbon atoms.

Both (b) and (c).

c

The alpha and beta forms of glucose, found in starch and cellulose, differ in ...

whether the first C atom is bound to one or two O atoms.

whether the molecule is a ring or an open chain.

how one of the -OH groups is oriented.

whether the ring contains five or six C atoms.

how one of the -OH groups is priented

A sugar can have ...

(a) H covalently bound to the C of a C=O group.

(b) a C atom that is covalently bound to three H atoms.

(c) the formula C5H8O5.

Both (a) and (c).

Both (b) and (c).

a

A cotton shirt is chemically most similar to a ...

pat of butter.

slice of ham.

sugar cube.

fingernail.

DNA double helix.

sugar cube

he bond that joins two monosaccharides into a disaccharide is a(n) _____.

ionic bond

van der Waals bond

glycosidic bond

hydrogen bond

glycosidic bond

What are three ways monosaccharides differ from one another?

the type of glycosidic linkage

the number of carbon atoms they contain

the orientations of the C-1 hydroxyl

the orientations of their hydroxyl groups

the location of their carbonyl group

the number of monomers in the molecule

the number of carbon atoms they contain

the orientations of their hydroxyl groups

the location of their carbonyl group

What is responsible for this change in taste?

Amylase breaks down the starch in the cracker into glucose monomers, which stimulate the sweet receptors in your tongue.

Suppose you discovered a new amino acid. Its R-group contains only hydrogen and carbon atoms. Predict the behavior of this amino acid.

it is hydrophobic

You disrupt all hydrogen bonds in a protein. What level of structure will be preserved?

primary structure

Words From Our Students

"StudyBlue is great for studying. I love the study guides, flashcards and quizzes. So extremely helpful for all of my classes!"

Alice, Arizona State University

"I'm a student using StudyBlue, and I can 100% say that it helps me so much. Study materials for almost every subject in school are available in StudyBlue. It is so helpful for my education!"

Tim, University of Florida

"StudyBlue provides way more features than other studying apps, and thus allows me to learn very quickly!??I actually feel much more comfortable taking my exams after I study with this app. It's amazing!"

Jennifer, Rutgers University

"I love flashcards but carrying around physical flashcards is cumbersome and simply outdated. StudyBlue is exactly what I was looking for!"